Big firm life is not for everyone because the grind never ceases, even for those who are young partners. Therefore, many chose to leave just to preserve their sanity. Whether by choice or not, anyone who leaves after having done a reasonable stint at such firms historically has had an open ticket to all sorts of other premier jobs within the legal profession (prominent in-house positions, partnership at mid-sized firms, senior government positions, etc.). This is another reason why associates scramble so hard to land positions within the largest firms. In essence, once you have proved yourself there even at the earliest stages, you have an open ticket to do well in the field generally from that day forward. Of course, this is not automatic and must be accompanied by lots of hard work, etc. One thing that is almost guaranteed about such lawyers is that they are highly disciplined lawyers who take their careers seriously and who seek to excel at what they do.